This invention relates generally to solar energy conversion systems that have trough reflectors and solar cell arrays; more specifically, this invention relates to an improved method of providing coolant for solar cell arrays that are exposed to concentrated sunlight produced by trough reflectors.
Trough reflectors concentrate incident radiation in one spatial dimension. They are frequently used in solar energy conversion systems to collect solar radiation and redirect it towards receiver assemblies.
A trough reflector system can have either of two types of receiver assemblies: thermal receiver assemblies or solar cell receiver assemblies. A thermal receiver assembly usually consists of a vacuum-jacketed cylindrical tube through which flows a fluid capable of withstanding temperatures of several hundred degrees. Concentrated solar radiation incident on the tube heats the fluid which is then passed through a heat exchanger (boiler) to produce steam for driving a heat engine.
A solar cell receiver assembly, on the other hand, cannot operate efficiently at high temperatures because it contains temperature-sensitive solar cells. In a trough reflector system with solar cell receiver assemblies, solar cell arrays are positioned so as to intercept concentrated solar radiation coming from the system's trough reflectors. Solar radiation incident on the solar cells generates electricity directly, without the need for a steam-cycle generator. If the intensity of the concentrated radiation falling on the solar cells is greater than a few suns, the solar cell arrays must be actively cooled in order to achieve best system performance. The present invention reveals an innovative improvement of the technology used for cooling the solar cell arrays. When implemented, this new technology provides important system simplifications, thereby increasing the reliability and reducing the cost of trough reflector systems that have solar cell receiver assemblies.